When discussing any topic, it is vitally
important that your basic assumptions are correct. It doesn't matter if you are
the most logical person in the world, if you begin your reasoning with "Elves
are running our government" your conclusion is more than likely going to be
incorrect. Here are some common mistakes when making assumptions in a debate.
1. Reaching definate conclusions based on generalizations Example:
Statistically, men are stronger than women. Therefore, no woman could every
outlift any man.
2. Ignoring other characteristics when reaching
conclusions Example: I am alive. Frogs are alive. Therefore, I am a
frog.
3. Ignoring observed phenomena in favor of what someone tells
you Example: I saw my husband kissing another woman in the park, but since
he said he was going out of town, it must have been someone else.
4.
Focusing on a single characteristic in a complex situation Example: OJ
Simpson was arrested for one reason: because he was black.
5. Using lack
of evidence to reach conclusions Example: I've never seen Bob punch anyone.
Therefore, he must be a wimp.
6. Circular Reasoning Example: Pete
carries an axe because he is a fireman, and we know he's a fireman because he
carries an axe.
7. Snowball Theory (also called the slippery slope)
Example: If I don't buy this candy bar the store could go broke, causing
people to lose their jobs and be unable to buy anything; which will cause a loss
in sales, a dropping of profits, and the companies will be forced to start
laying people off, which could result in a depression; this would mean a drop in
stocks, a loss of money, mass suicides, banks running out of money, and finally
the total collapse of western society. So I'd better buy this candy
bar.
8. Failing to recognize essential characteristics. Example: An
axe with a seven inch blade will break down a door in twenty seconds, so a four
inch knife should be able to do it in forty seconds. Cause and
Effect Mistakes Cause and effect are important things to consider in
certain areas of discussion, especially in history or the applied sciences.
Obviously cause and effect are a chain of events: what affects one thing effects
something else, and so on. Here are some of the more common mistakes in logical
thinking when people are discussing causes and effects.
1. Confusing
Cause with Effect Example: Wearing large dresses makes you look
fat.
2. Failing to recognize multiple Causes Example: The Roman Empire
fell because the barbarians invaded.
3. Confusing independent events with
Cause and Effect Example: Napolean sold Louisiana to America. Napolean lost
at Waterloo. Therefore, if Napolean had kept Louisiana he would have
won.
4. Not recognizing a cause-effect relationship Example: What
does not exercising have to do with my weight problem?
5. Confusing a
correlation with cause and effect Example: Serial killers chew gum.
Therefore, they kill because of gum.
6. Assuming cause-effect rather than
coincidence Example: John is a doctor. Paul killed John. Therefore, Paul
killed John because he was a doctor.
7. Failure to recognize multiple
Effects Example: Hitler's a good guy, since he improved Germany's
economy.
8. Failure to recognize that a cause doesn't always lead to the
effect. Example: I've smoked for years and haven't gotten cancer, therefore
smoking doesn't cause cancer.
Theories and Occam's
Razor "plurality should not be posited without necessity" wrote
William of Ockham almost seven hundred years ago. The idea he was trying to
convey, the idea we today call "Occam's Razor" is that if there is more than one
theory that explains something, and both are equally valid, the simpler one
should be assumed to be the correct one. For example, scientists at the
start of this century believed in an unmeasurable substance called "Ether". It
was to explain a great many ideas of physics. The theory of ether was eventually
discarded because scientists were able to explain things just as well without
ether, so ether was an unnecessary part of physics. This is an example of
applying Occam's Razor; choosing a simpler theory out of two when both equally
explain all the facts. What follows are mistakes people make with theories in
general and Occam's Razor in particular.
1. Ignoring Occam's
Razor Example: Sure, the Mayans could have been wiped out by a disease, but
isn't it just as likely that they were carried off by aliens?
2.
Mis-applying Occam's Razor Example: The simplest explanation for the Apollo
moon landings is that they were faked.
3. Failing to understand that
one theory can't always explain everything Example: Your theory on bacteria
doesn't explain why yogurt tastes good, so it must be wrong.
4.
Reaching a conclusion with no evidence Example: The Roanoke colony
disappeared because they developed time travel technology.
5. Giving
equal balance to a theory who's only strength is that it cannot be
disproved. Example: You can't prove gnomes don't exist, so it's just as
reasonable to assume that they do.
6. Demanding opponents disprove your
theory rather than you supporting it. Example: Prove that a monkey can't be
trained to juggle.
7. Confusing theory with evidence. Example:
Denying that the sun goes around the earth is admitting you are ignoring the
evidence of your own eyes.
Faulty
Analogies Analogies are a great way to convey ideas: take a simple
comparison and apply it to something more complex. For example, a colony depends
on a country the way a child depends on its parent. However, analogies are also
an area where logic falls apart, and all sorts of bizarre conclusions can be
reached.
1. Applying a flawed analogy to an argument Example: You can
get a computer to control a rocket, therefore you can get your toaster to
drive your car.
2. Extending an analogy beyond its logical
limits Example: Electricity flows through wires like water through a hose.
Therefore, you can stop the electricity by pinching the cord.
3.
Extrapolation without understanding the mechanics involved Example: You can
train a dog to fetch a stick, therefore you can train it to play
the piano.
4. Extrapolation beyond all logic Example: I can lift
two hundred pounds easily. Therefore, I can pick up the Sear's Tower.
5.
Irrelevant comparisons Example: A cow's a better pet than a sperm
whale.
Experts Experts are just that: someone
who has demonstrated that they have a great deal of knowledge in a certain area.
Of course, experts can and do make mistakes, but it would be silly to ignore the
advice of an expert on the possibility that they may be in error when you are
not an expert yourself. The most important thing to do is consider what the
expert says. Is it logical? Is it consistent? Does it agree with what is known
on the subject? Can general statements be verified? An expert should not be
followed like lemmings, but nor should their expertise be ignored.
1.
Ignoring the information of an expert without reason Example: You may have a
degree in medicine, but I still don't believe I have a spleen.
2.
Intelligence by osmosis Example: My mother is a lawyer, so I know what you're
doing is illeagal.
3. Failing to realize that information is lost when
passed along Example: I told my Chemistry professor your theory on chemical
bonds and he thinks it's wrong, so it must be.
4. Accepting the advice
of a known idiot Example: I know Bill said that it rains donuts, but that
doesn't mean he doesn't know anything about weather.
5. Considering
oneself an expert with no training Example: Who says you need to go to
school to learn demolitions.
6. Failure to grasp statistics Example: I
won three games of Russian Roulette, therefore the game is
safe.
Deceitfulness The first completely
new category added to logical flaws. These arguements are usually employed by
someone who is deliberately trying to cloud the issue rather than discuss things
rationally. Not exactly stupid, they take great effort to accomplish
nothing.
1. The Strawman tactic (attributing foolish arguments to your
opponent) Example: You say that perjurers should go to jail, but all perjury
is is lying. Quite frankly, it's absurd to throw all lyars in prison, and you're
a fool for thinking so.
2. Claiming to be misquoted Example: I didn't
mean that Hitler was a good guy, just that I could see why someone might think
he's a good guy.
3. The magicians tactic(distracting away from the issue)
Example: My dog was not on your lawn, and why haven't your bushes been
trimmed.
4. Ignoring the issue by accusing the opponent Example:
Guess what Mr. Kettle, you're black.
5. Making the opponent the issue
instead of the argument Example: That sounds just like something a bigot
would say.
6. Characterizing the opponent Example: Of course you
don't agree with my theory; most people with prejudices don't.
Plain Stupidity Crossing all kinds of logical boundaries, these
are ideas that show the world that not only are you illogical, you are also an
idiot. Avoid them like the plague!
1. Assuming that everyone is like
you Example: I don't know anything about Biology, therefore you don't
either.
2. Failure to understand that words have definitions Example:
The president isn't a criminal just because he broke the law.
3.
Believing special circumstances are the norm Example: A doctor stole a man's
kidney to make money. Therefore, all doctors are untrustworthy and
greedy.
4. Failure to grasp what is real Example: If I had to, I could
deliver a baby. I've seen it hundreds of times on television.
5.
Demonstrating that common sense requires effort on your part Example: If we
could drive faster, we'd get there much sooner.
6. Demonstrating supreme
ignorance in the topic being discussed Example: If we just print more money,
everybody could be rich.
7. Attacking the opponent instead of the
argument Example: Sure, you know more about literature, but that's because I
have a life
8. Attempting to use stereotypes as logical facts Example:
A woman can never become president because they spend too much time buying
shoes.
9. Blatant hypocrisy Example: Only a brainless idiot with his
head up his butt would behave as rudely as you do!
10. Demanding the
Impossible Example: I will not accept General Relativity unless I am sent a
letter by Albert Einstein himself.
11. Thinking everyone who disagrees
with you has the same argument Example: If you're not a Catholic, then you
must be an athiest.
12. Believing research is required to state the
obvious Example: You haven't even bothered looking at Zeppler's Zoology
book, so what makes you think you can tell me that fish don't have
hair?
13. Complete close-mindedness Example: I am right and you are
wrong, I won't speak to you any more on this.
14. Believing "possible"
makes something likely Example: It's possible AIDS was created by the CIA,
therefore, we should get rid of the CIA so they won't do it again.
15.
Self-contradicting coupled with a refusal to consider alternate
theories (thanks to Graeme Dice for the example) Example: Someone hands
me something they call a "hat", although it looks exactly like a shoe. Despite
it looking like a shoe, I put it on my head anyway. I then claim that the
manufacturers of this "hat" are idiots, because it looks like a shoe and not a
hat.
16. Questioning known facts only because they hurt your argument
Example: Your theory doesn't take into account the possibility that George
Washington may still be alive.
17. Taking quotes out of context.
Example: "Everything that's supposed to be down is up." This quote by Al
Gore shows his opposition to Clinton's sexual practices.
18. Believing
something is possible if it hasn't been tried Example: Perhaps if we all
line up on the shore and blow at the same time, the hurricane will change
direction.
19. I am the world Example: I will not allow the tyranny
of the majority to force me to wear pants.
20. Making assumptions without
evidence Example: We can calculate the moon's mass by using the density of
cheese, which is what the moon is made of.
21. My unproven assumptions
are the only reasonable ones Example: It's ludicrous that you believe a
nuclear bomb is over a trillion times the power of a stick of dynamite; it's
probably only about a billion.
22. One means all. Example: If Bill,
Tom, and Fred are in a room and Jane slaps Bill, she must also have slapped Tom
and Fred.
23. Delusions of Mediocrity (believing one's theories are being
ignored by short-sited people when in reality you're just wrong). Example:
People laughed at Einstein too, but what does history say about him? That he was
right. You'll see.....
24. Assuming an single member of a group
represents all members of that group(cr: Dave). Example: Brian, a Rolling
Stones fan, likes to eat peanuts. Therefore, all Rolling Stones fans like to eat
peanuts.
